by jim@foreignaffairs » Mon May 24, 2004 1:32 pm
On my car I ruled out the original filter only because I replaced it. During R&D I did bump up my fuel pressure by modifying the stock fuel pressure regulator to 55 psi. I used an very high output Walbro pump and Supra injectors. But things just didn't feel right, like I was hitting some sort of wall. That's when I decided to test the fuel pressure at the front rail. I hooked up a gauge on a line that I could read as I drove. At about 3500 rpm I mashed on the throttle, and the pressure went from 55 down to 42psi, about a 27% drop. That's huge. Well I went straight to the shop and replaced the whole fuel system with way overkill. The end result was a big increase in midrange power, no more knock sensor backing off timing. I think the stock fuel system feeding the rear injectors first and then the front is a major problem, and the fuel filter is restrictive, so I put together a fuel filter and hose kit that eliminates these problems. If you test your fuel pressure at the front rail and have no decrease in fuel pressure than everything is OK with your stock system. But if you do, you should fix it.
Something else I think you should know is that I didn't put together a fuel system upgrade kit until several peopled begged me to. It is more trouble than it is worth for me to send these out, as I own an auto shop, and my time is better spent fixing cars. I just though I would pass on my experiences in the hope all could benefit, and send the stuff to use in case you are not able to put it together yourself, which many have done already. So in other words, I am not trying to sell you this to make money. I am just tired of people crying about spending several hundred dollars replacing knock sensors when the problem is fuel delivery to the front rail. If you want to put the fuel upgrade together yourself just call me and I'll tell you what to get.
Jim 503-236-2871